Energy absorbing system for fixed roadside hazards

ABSTRACT

An energy absorbing system with one or more energy absorbing assemblies is provided to reduce or eliminate the severity of a collision between a moving motor vehicle and a roadside hazard. The energy absorbing system may be installed adjacent to a roadside hazard such as the end of a concrete barrier facing oncoming traffic. The energy absorbing system preferably includes at least one energy absorbing element. A sled assembly is also provided with a cutter plate such that a collision by the motor vehicle with one end of the sled assembly will result in the cutter plate tearing or ripping the energy absorbing element to dissipate energy from the motor vehicle collision. The configuration and number of energy absorbing assemblies and the configuration and number of energy absorbing elements may be varied depending upon the intended application for the resulting energy absorbing system.

RELATED APPLICATIONS

This application claims the benefit of previously filed provisionalapplication Ser. No. 60/096,538 filed Aug. 13, 1998 entitled EnergyAbsorbing System for Fixed Roadside Hazards.

This application is a continuation-in-part application of U.S. Ser. No.08/870,118 filed Jun. 5, 1997, entitled Energy Absorbing Crash Cushion,now U.S. Pat. No. 5,947,452.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to the field of impact attenuationdevices, and more particularly to an energy absorbing system which maybe used to reduce the severity of a collision between a moving motorvehicle and a stationary hazard adjacent to a roadway.

BACKGROUND OF THE INVENTION

Various impact attenuation devices and energy absorbing systems havebeen used to prevent or reduce damage resulting from a collision betweena moving motor vehicle and a fixed roadside hazard or obstacle. Examplesof prior impact attenuation devices and energy absorbing systems includecrash cushions or crash barriers with various structures and containershaving crushable elements. Other crash barriers rely on inertia forcesgenerated when material such as sand is accelerated during an impact toabsorb energy.

Some of these devices and systems have been developed for use at narrowroadside hazards or obstacles such as at the end of a median barrier,end of a barrier extending along the edge of a roadway, large sign postsadjacent to a roadway, and bridge pillars or center piers. Such impactattenuation devices and energy absorbing systems are installed in aneffort to minimize the extent of personal injury as well as damage to animpacting vehicle and any structure or equipment associated with theroadside hazard.

Examples of general purpose impact attenuation devices are shown in U.S.Pat. No. 5,011,326 entitled Narrow Stationary Impact Attenuation System;U.S. Pat. No. 4,352,484 entitled Shear Action and Compression EnergyAbsorber; U.S. Pat. No. 4,645,375 entitled Stationary Impact AttenuationSystem; and U.S. Pat. No. 3,944,187 entitled Roadway Impact Attenuator.Examples of specialized stationary energy absorbing systems are shown inU.S. Pat. No. 4,928,928 entitled Guardrail Extruder Terminal and U.S.Pat. No. 5,078,366 entitled Guardrail Extruder Terminal. Each of thepreceding patents is incorporated by reference for all purposes in thepresent application.

Examples of impact attenuation devices and energy absorbing systemsappropriate for use on a slow moving or stopped highway service vehicleare shown in U.S. Pat. No. 5,248,129 entitled Energy Absorbing RoadsideCrash Barrier; U.S. Pat. No. 5,199,755 entitled Vehicle ImpactAttenuating Device; U.S. Pat. No. 4,711,481 entitled Vehicle ImpactAttenuating Device; U.S. Pat. No. 4,008,915 entitled Impact Barrier forVehicles.

Recommended procedures for evaluating performance of various types ofhighway safety devices including crash cushions is presented in NationalCooperative Highway Research Program (NCHRP) Report 350. A crash cushionis generally defined as a device designed to safely stop an impactingvehicle within a relatively short distance. NCHRP Report 350 furtherclassifies crash cushions as either “redirective” or “nonredirective”. Aredirective crash cushion is designed to contain and redirect a vehicleimpacting downstream from a nose or end of the crash cushion facingoncoming traffic extending from a roadside hazard. Nonredirective crashcushions are designed to contain and capture a vehicle impactingdownstream from the nose of the crash cushion. Redirective crashcushions are further classified as either “gating” or “nongating”devices. A gating crash cushion is one designed to allow controlledpenetration of a vehicle during impact between the nose of the crashcushion and the beginning of length of need (LON) of the crash cushion.A nongating crash cushion is designed to have redirection capabilitiesalong its entire length.

SUMMARY OF THE INVENTION

In accordance with teachings of the present invention, disadvantages andproblems associated with the previous impact attenuation devices andenergy absorbing systems have been substantially reduced or eliminated.One aspect of the present invention includes providing a crash barrieror crash cushion which may be installed adjacent to a fixed roadsidehazard or obstacle to protect occupants of a vehicle from collision withthe roadside hazard. The crash cushion preferably includes a cutterplate and a series of rip plates or energy absorbing elements whichcooperate with each other to absorb energy from a vehicle impacting oneend of the crash cushion opposite from the fixed roadside hazard. Therip plates remain relatively fixed within the crash cushion while thecutter blade moves through the rip plates to absorb energy from thevehicle impact. The crash cushion also includes improved panels andassociated panel support frames to redirect a vehicle impacting witheither side of the crash cushion.

Another aspect of the present invention includes providing an energyabsorbing system having a plurality of panel support frames and panelswhich may be installed between a road side hazard and oncoming traffic.The panel support frames and panels are slidably disposed relative toeach other. As a result, when a vehicle collides with one end of theenergy absorbing system facing oncoming traffic, the panel supportframes and panels will telescope or collapse relative to each other tocushion the impact from the vehicle. The panel support frames,associated panels and other components of the energy absorbing systemcooperate with each other to absorb kinetic energy from the vehicle andprovide deceleration within acceptable limits to minimize injury tooccupants within the vehicle. The panel support frames and panels alsocooperate with other components of the energy absorbing system to directvehicles away from the road side hazard and back onto the roadwayfollowing a collision with either side of the energy absorbing system.

Technical advantages of the present invention include providing a crashcushion which may be fabricated at relatively low cost usingconventional materials and processes that are well known to the highwaysafety industry. The resulting crash cushion combines innovativestructural and energy absorbing techniques that are highly predictableand reliable. Energy from vehicle impact is preferably absorbed byripping, cutting or tearing one or more energy absorbing elements. Thecrash cushion may be easily reused following vehicle impact by replacingone or more energy absorbing elements. A wide variety of metal stripsand metal plates may be satisfactorily used as energy absorbing elementsdepending upon the intended operating environment for the crash cushion.Also, the number of energy absorbing elements and their geometricconfiguration may be varied depending upon the intended application.

In accordance with another aspect of the present invention, a crashcushion is provided with multiple energy absorbing elements disposedadjacently to one end of a fixed roadside hazard facing oncomingtraffic. The energy absorbing elements cooperate with each other toallow varying the amount of deceleration applied to a vehicle impactingone end of the crash cushion opposite from the fixed roadside hazard.For example, the crash cushion may include a first, relatively softportion to absorb impact from small, lightweight vehicles, a middleportion with increased stiffness and a third or final portion with thegreatest amount of stiffness to absorb impact from heavy, high speedvehicles.

Still another aspect of the present invention includes providing a crashcushion with multiple panels which are preferably nested with each otherto minimize any problems associated with a “reverse angle” impactbetween a vehicle and either side of the crash cushion. The panels andassociated panel support frames preferably telescope with respect toeach other in response to a vehicle impact at one end of the crashcushion opposite from the fixed roadside hazard. The number of panelsupport frames and associated panels may be selected in accordance withteachings of the present invention to optimize deceleration of animpacting vehicle while protecting occupants of the vehicle from injurydue to excessive amounts of deceleration.

Further technical advantages of the present invention include providingrelatively low cost crash cushions which meet the criteria of NCHRPReport 350 including Level 3 Requirements. A crash cushion having acutter plate and energy absorbing elements incorporating teachings ofthe present invention may be satisfactorily used during harsh weatherconditions and is not sensitive to cold or moisture. A cutter plate andenergy absorbing elements incorporating teachings of the presentinvention can absorb large amounts of energy while safely stopping animpacting vehicle during a relatively short length of travel of thecutter plate through the energy absorbing elements.

The cutter plate and energy absorbing elements cooperate with each otherand with panel support frames and associated panels to eliminate many ofthe problems associated with prior crash cushion designs. A crashcushion incorporating teachings of the present invention cansatisfactorily dissipate kinetic energy of an impacting vehicle weighing4,500 pounds at speeds of over sixty miles per hour (60 mph) withminimal damage (if any) to the roadside hazard and minimal debris (ifany) from the crash cushion. A crash cushion incorporating teachings ofthe present invention provides highly predictable deceleration of animpacting vehicle to protect occupants of the vehicle.

In addition to eliminating problems associated with prior crash cushiondesigns, the present invention provides a crash cushion offering ahigher level of protection to the motoring public with greater improvedreliability and reduced costs. The resulting crash cushion providesappropriate deceleration or stopping force for a wide range of vehiclesizes and types including vehicles weighing between 820 kilograms and2,000 kilograms.

A further aspect of the present invention includes a crash cushionhaving a sled assembly with a cutter plate attached thereto and multipleenergy absorbing assemblies connected with each other by a series ofcross ties or anchor plates. As a result of connecting the energyabsorbing assemblies with each other, the crash cushion has a rigidframe construction which in cooperation with multiple panel supportingframes and associate panels will redirect vehicles during side impactswith the crash cushion.

For some applications each energy absorbing assembly includes twoC-channels with the C shaped configurations facing each other and theC-channels extending generally horizontally in the direction of oncomingvehicle traffic during normal operation of the crash cushion. A gap ofapproximately one inch is provided between opposing flanges of the twoC-channels. This gap may be covered by one or more metal plates orenergy absorbing elements to form a closed box type structure. A cutterblade or ripper is preferably attached to the lower portion of a sledassembly at the end of the crash cushion facing oncoming traffic. Duringimpact between a motor vehicle and the sled assembly, forces from thecollision are transferred from the sled assembly to the energy absorbingassemblies by the cutter blade. As the sled assembly moves toward thefixed roadside hazard, the metal plates or energy absorbing elementswhich are attached on opposite sides of the C-channels are cut or rippedby the cutter blade. The energy of the impacting vehicle is dissipatedand the impacting vehicle brought safely to rest by the force requiredto cut or rip the metal plates of the energy absorbing assemblies.Various combinations of metal plates and supporting beams may be used toform each energy absorbing assembly to provide appropriate stopping ordeceleration for a wide range of vehicle types, weights and speeds ofimpact. Supporting beams having configurations other than C-channels maybe satisfactorily used with the present invention.

Technical advantages of the present invention include providing a crashcushion which may be easily installed, operated and maintained. Easilyreplaceable parts allow quick, low cost repair after nuisance hits andside impacts. Elimination of easily crushed or easily bent materialsfurther minimizes the effect of any damage from nuisance hits and/orside impacts with the crash cushion.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be acquiredby referring to the following description taken in conjunction with theaccompanying drawings in which like reference numbers indicate likefeatures and wherein:

FIG. 1 is a schematic drawing showing an elevational view with portionsbroken away of an energy absorbing system incorporating teachings of thepresent invention installed adjacent to one end of a fixed roadsidehazard;

FIG. 2 is a schematic drawing showing a plan view with portions brokenaway of the fixed roadside hazard and energy absorbing system of FIG. 1;

FIG. 3 is a schematic drawing showing an isometric view with portionsbroken away of a cutter plate and an energy absorbing assembly having aplurality of energy absorbing elements and supporting beamsincorporating teachings of the present invention;

FIG. 4 is a schematic drawing in section with portions broken away takenalong lines 4—4 of FIG. 3 showing the box beam type cross section of theenergy absorbing assembly;

FIG. 5 is a schematic drawing showing an isometric view with portionsbroken away of the energy absorbing assembly of FIG. 3 after the energyabsorbing elements have been cut or ripped while absorbing energy from avehicle impact;

FIG. 6 is a schematic drawing in section with portions broken awayshowing an energy absorbing assembly incorporating another embodiment ofthe present invention;

FIG. 7 is an exploded schematic drawing showing an isometric view withportions broken of still another embodiment of the present invention inwhich the energy absorbing assembly includes a plurality ofprogressively thicker energy absorbing elements or metal plates alongthe length of the associated energy absorbing assembly selected to stopan impacting automobile with a gradually increasing deceleration orstopping force applied to the impacting automobile;

FIG. 8 is a schematic drawing showing an isometric view with portionsbroken away of an energy absorbing element having a plurality of cutoutsdisposed therein to minimize damage to a light weight motor vehicleduring initial impact with an energy absorbing assembly having suchenergy absorbing elements;

FIG. 9A is a schematic drawing showing a plan view with portions brokenaway of another energy absorbing system incorporating teachings of thepresent invention installed adjacent to one end of a fixed roadsidehazard;

FIG. 9B is a schematic drawing showing a plan view with portions brokenaway after a motor vehicle has collided with or impacted one end of theenergy absorbing system of FIG. 9A opposite from the fixed roadsidehazard;

FIG. 9C is a schematic drawing showing a plan view of still anotherenergy absorbing system incorporating teachings of the present inventioninstalled adjacent to one end of a fixed roadside hazard;

FIG. 10 is a more detailed schematic drawing showing an elevational viewwith portions broken away of the energy absorbing system shown in FIGS.9A and 9B;

FIG. 11 is a schematic drawing with portions broken away showing anisometric view of a sled assembly and other components at the end of theenergy absorbing system of FIG. 10 opposite from the fixed roadsidehazard;

FIG. 12 is a schematic drawing with portions broken away showing anisometric view of the sled assembly associated with the energy absorbingsystem of FIG. 10;

FIG. 13 is a schematic drawing end section with portions broken awayshowing one end of the sled assembly of FIG. 12 opposite from oncomingtraffic;

FIG. 14 is a schematic drawing with portions broken away showing anexploded isometric view of the sled assembly, cutter plate and rampassociated with the energy absorbing system of FIG. 10;

FIG. 15 is a schematic drawing end section with portions broken awaytaken along lines 15—15 of FIG. 10 showing a slidable support frame andattached panels;

FIG. 16 is a schematic drawing with portions broken away showing anisometric view of the slidable support member and attached panels asshown in FIG. 15;

FIG. 17 is a schematic drawing showing an isometric view of overlappingpanels incorporating teachings of the present invention disposed alongone side of the energy absorbing system of FIG. 10;

FIG. 18 is a schematic drawing end section with portions broken awayshowing a first upstream panel and a second downstream panel slidablydisposed relative to each other in accordance with teachings of thepresent invention;

FIG. 19 is a schematic drawing showing an isometric view of a slot platesatisfactory for use in slidably attaching a panel incorporatingteaching of the present invention with a panel support frame; and

FIG. 20 is a schematic drawing with portions broken away showing anexploded plan view of a cutter plate and energy absorbing elementssatisfactory for use with the energy absorbing system of FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

The present invention and its advantages are best understood byreferring to FIGS. 1-20 of the drawings, like numerals being used forlike and corresponding parts of the drawings.

Energy absorbing system 320 incorporating one embodiment of the presentinvention is shown in FIGS. 1 and 2. Energy absorbing system 20incorporating additional embodiments of the present invention is shownin FIGS. 9A-20. Energy absorbing systems 20 and 320 may sometimes bereferred to as crash cushions, crash barriers, or roadside protectivesystems. Energy absorbing systems 20 and 320 may be used to minimize theresults of a collision between a motor vehicle (not expressly shown) andvarious types of roadside hazards such as roadside hazard 310.

A wide variety of energy absorbing assemblies may be fabricated inaccordance with the teachings of the present invention by attachingenergy absorbing elements or metal plates with a pair of supportingbeams spaced from each other. A cutter plate with one or more cuttingedges may be disposed adjacently to the energy absorbing elementsbetween the supporting beams to dissipate kinetic energy by ripping ortearing the associated energy absorbing elements. An energy absorbingsystem incorporating teachings of the present invention may be formedfrom energy absorbing assemblies and/or panel support frames and panelsslidably disposed relative to each other. The energy absorbingassemblies, panel support frames and panels may be selected tosatisfactorily absorb energy from a wide variety of vehicles collidingwith the energy absorbing system at various angles including sideimpacts and “reverse” angle side impacts.

Energy absorbing systems 20 and 320 are shown installed at the end ofroadside hazard 310 facing oncoming traffic. Roadside hazard 310 shownin FIGS. 1, 2, 9A, 9B, and 10, may be a concrete barrier extending alongthe edge or side of a roadway (not expressly shown). Roadside hazard 310may also be a concrete barrier extending along the median between tworoadways.

The terms “longitudinal,” “longitudinally” and “linear” will generallybe used to describe the orientation and/or movement of componentsassociated with energy absorbing systems 20 and 320 in a direction whichis substantially parallel with the direction vehicles (not expresslyshown) will travel on an adjacent roadway. The terms “lateral” and“laterally” will generally be used to describe the orientation and/ormovement of components associated with energy absorbing systems 20 and320 in a direction which is generally normal to the direction vehicleswill travel on the adjacent roadway.

The term “downstream” will generally be used to describe movement whichis substantially parallel with and in the same direction as movement ofa vehicle traveling an adjacent roadway. The term “upstream” willgenerally be used to describe movement which is parallel with butopposite to the direction a vehicle travels on an adjacent roadway. Theterms “upstream” and “downstream” may also be used to describe theposition of one component relative to another component in respectiveenergy absorbing systems 20 and 320.

The terms “separate” and “separating” will generally be used to describethe results of deforming an energy absorbing element using a cutterplate to cause failure of the energy absorbing element in tension inaccordance with teachings of the present invention. The terms “separate”and “separating” may also be used to describe the combined effects ofripping and tearing an energy absorbing element in accordance withteachings of the present invention.

Various components of energy absorbing systems 20 and 320 may be formedfrom commercially available structural steel materials. Examples of suchmaterials include steel strips, steel plates, structural steel tubingand structural steel shapes. Examples of structural steel shapes includeW shapes, HP shapes, beams, channels, tees, and angles. Structural steelangles may have legs with equal or unequal width. The American Instituteof Steel Construction publishes detailed information concerning varioustypes of commercially available steel structural materials satisfactoryfor use in fabricating energy absorbing systems 20 and 320.

Roadside hazard 310 may sometimes be described as a “fixed” barrier or“fixed” obstacle even though concrete barriers and other obstaclesadjacent to a roadway may from time to time be moved or removed.Roadside hazard 310 may also represent a portion of a large sign postadjacent to a roadway, a bridge pillar, a center pier of a bridge oroverpass, or any other structure located adjacent to a roadway andpresenting a hazard to oncoming traffic. An energy absorbing systemincorporating teachings of the present invention is not limited to usewith only concrete barriers.

Principal components of energy absorbing system 320 as shown in FIGS. 1,2, and 3 preferably include one or more energy absorbing assemblies 86,cutter plate or plates 106 and sled assembly 340. Cutter plate 106 mayalso be referred to as a “ripper” or as a “cutter blade.”

One end of each energy absorbing assembly 86 is preferably attached toroadside hazard 310 by respective struts 312. For some applicationsenergy absorbing assemblies 86 may also be fixed to the ground in frontof roadside hazard 310. A plurality of spacers or cross braces 314 maybe used to hold energy absorbing assemblies 86 aligned generallyparallel with each other and extending longitudinally from roadsidehazard 310 toward oncoming traffic.

Sled assembly 340 is slidably coupled with the end of energy absorbingassemblies 86 opposite from roadside hazard 310. Impact plate 382 may bedisposed on the end of sled assembly 340 facing oncoming traffic. One ormore of cutter plates 106 (not shown in FIGS. 1 and 2) are preferablyprovided as part of sled assembly 340. Respective cutter plates 106 arepreferably slidable mounted relative to one end of each energy absorbingassembly 86 opposite from roadside hazard 310. When a motor vehicle (notexpressly shown) contacts or collides with impact plate 382, sledassembly 340 will move longitudinally relative to energy absorbingassemblies 86 and roadside hazard 310. As sled assembly 340 moves towardroadside hazard 310, kinetic energy of the impacting motor vehicle willbe dissipated by cutter plates 106 tearing or ripping associated energyabsorbing elements 100. For some applications it may be desirable toinstall a section of guardrail 316 between roadside hazard 310 and sledassembly 340 on the side immediately adjacent to the roadway.

For the embodiment of the present invention as shown in FIGS. 3, 4, and5, energy absorbing assembly 86 may sometimes be referred to as a “boxbeam.” Each energy absorbing assembly 86 preferably includes a pair ofsupporting beams 90 which are disposed longitudinally parallel with eachother and are spaced from each other. Supporting beams 90 have agenerally C-shaped or U-shaped cross section. The C-shaped cross sectionof each supporting beam 90 is disposed facing each other to define agenerally rectangular cross section for energy absorbing assembly 86.Supporting beams 90 may also be described as channels. The C-shapedcross section of each support beam 90 is defined in part by web 92 andgrips or flanges 94 and 96 extending therefrom. A plurality of matchingholes 98 are preferably formed in both grips 94 and 96 for use inattaching energy absorbing elements 100 to opposite sides of energyabsorbing assembly 86.

For the embodiment shown in FIGS. 3, 4, and 5, a pair of energyabsorbing elements 100 is attached to grips 94 on one side of energyabsorbing assembly 86. Another pair of energy absorbing elements 100 isattached to grips 96 on the opposite side of energy absorbing assembly86. Spacers 104 are preferably disposed between each pair of energyabsorbing elements 100 adjacent to the respective grips 94 and 96. Aplurality of fasteners 103 extend through holes 98 in grips 94 and 96and the associated energy absorbing elements 100. For the embodiment ofthe present invention shown in FIGS. 3, 4 and 5, energy absorbingelements 100 have a relatively uniform thickness. As discussed later inmore detail with respect to energy absorbing assembly 486 shown in FIG.7 and energy absorbing elements 152 a, b, c and d shown in FIG. 20, itmay be desirable to vary the thickness and/or number of energy absorbingelements extending along the length of an energy absorbing assembly.

Fasteners 103 allow easy replacement of energy absorbing elements 100after collision of a motor vehicle with impact plate 382. A wide varietyof fasteners may be satisfactorily used to attach energy absorbingelements 100 with supporting beams 90.

Energy absorbing elements 100 may be formed from various types of metalalloys. For some applications, mild steel is preferred. The number ofenergy absorbing elements 100 and their length and thickness may bevaried depending upon the intended application for the resulting energyabsorbing assembly. Increasing the number of energy absorbing elements,increasing their thickness, and/or increasing the length of energyabsorbing elements 100, will allow the resulting energy absorbingassembly to dissipate an increased amount of kinetic energy. Energyabsorbing elements 100 may also be referred to as rip plates or shearplates. Benefits of the present invention include the ability to varythe geometric configuration and number of energy absorbing elements 100and to select appropriate metal alloys depending upon the intendedapplication for the resulting energy absorbing system.

For the embodiment shown in FIG. 3, cutter plate 106 includes a pair ofbeveled cutting edges or ripping edges 107 and 109 which are disposed atfirst end 101 of respective energy absorbing assembly 86. Cutting edges107 and 109 may also be described as rip blades. The thickness of cutterplates 106 and gap 118 between supporting beams 90 are selected to allowcutter plate 106 to fit between grips 94 and 96 and the adjacentsupporting beams 90.

Slots 102 are preferably formed in the end of each energy absorbingelement 100 adjacent to respective cutter plate 106. Cutting edges 107and 109 are preferably disposed at an acute angle relative to energyabsorbing elements 100. For the embodiment shown in FIG. 3, cuttingedges 107 and 109 are hardened and formed at an angle of approximatelyforty-five degrees relative to the associated energy absorbing elements100. The configuration of cutting edges 107 and 109, including theirorientation relative to energy absorbing elements 100, is selected tocause the associated energy absorbing elements 100 to fail in tension asthey are stretched between the respective grips 94 and 96 of theassociated support beams 90.

Energy absorbing elements 100 and other metal components of energyabsorbing system 320 are preferably galvanized to insure that theyretain their desired tensile strength and are not affected byenvironmental conditions which could cause rust or corrosion during thelife of the associated energy absorbing system 320. Specific dimensionsof cutting edges 107 and 109, along with their angular relationshiprelative to energy absorbing elements 100, may be varied depending uponthe amount of kinetic energy which will be dissipated by energyabsorbing assembly 86.

When a motor vehicle collides with or contacts impact fence 382, theforce of the collision or impact is transmitted to energy absorbingassemblies 86 by cutter plate 106. As sled assembly 340 slideslongitudinally toward roadside hazard 310, the kinetic energy of animpacting vehicle is dissipated through cutting or ripping of energyabsorbing elements 100 by cutter plate 106 as shown, for example, inFIG. 5.

For relatively low speed impacts, such as between approximately fivemiles per hour and eighteen miles per hour or higher, one or morerelatively short lengths of energy absorbing elements 100 may beinstalled immediately adjacently to cutter plate 106. Thus, following alow speed impact only relatively short lengths of energy absorbingelements 100 will require replacement which substantially simplifiesrepair and maintenance of energy absorbing system 320.

As shown in FIG. 2, energy absorbing assemblies 86 are preferablysecured to each other by a plurality of cross braces 314. Cooperationbetween impact fence 382, cross braces 314 and energy absorbingassemblies 86 results in energy absorbing system 320 having a very rigidframe structure. As a result, energy absorbing system 320 is better ableto safely absorb impact from a motor vehicle that strikes impact fence382 either offset from the center of impact fence 382 or that strikesimpact fence 382 at an angle other than parallel with energy absorbingassemblies 86.

Energy absorbing assemblies 186 and 486 incorporating alternativeembodiments of the present invention are shown respectively in FIGS. 6and 7. Energy absorbing assemblies 186 and 486 may be satisfactorilyused with energy absorbing systems 20 and 320. Energy absorbing assembly186 shown in FIG. 6 includes a pair of supporting beams or channels 190similar to previously described supporting beams 90 for energy absorbingassembly 86. Energy absorbing assembly 186 is shown with only two energyabsorbing elements or rip plates 152 disposed on opposite sides thereof.Channels 190 are spaced from each other to define cutting zone or gap154 therebetween.

Energy absorbing elements 152 may be attached to supporting beams 190using various types of fasteners including bolts 103 as previouslydescribed for energy absorbing assemblies 86. Mechanical fasteners 198 aand 198 b as shown in FIGS. 13,15 and 16 may also be used to attachenergy absorbing elements 152 with supporting beams 190. Alternatively,energy absorbing elements 152 may be attached to supporting beams 190using other types of fasteners such as Huck bolts, rivets, by welding orby various adhesives. One of the main requirements is attaching energyabsorbing elements 152 with supporting beams 190 to provide anappropriately sized cutting zone 154 between supporting beams 190 toaccommodate the associated cutter plate (not shown). Energy absorbingassemblies having other configurations such as shown in correspondingU.S. patent application Ser. No. 08/870,118 filed Jun. 5, 1997 (now U.S.Pat. No. 5,947,452) may be satisfactorily used with an energy absorbingsystem incorporating teachings of the present invention.

FIG. 7 is an exploded schematic drawing showing energy absorbingassembly 486. Some of the differences between energy absorbingassemblies 86 and energy absorbing assembly 486 include variations inthe length and thickness of the energy absorbing elements which arereplaceably secured to energy absorbing assembly 486. Energy absorbingassembly 486 may be formed using supporting beams 90 as previouslydescribed with respect to energy absorbing assembly 86.

For one application, supporting beams or C-channels 90 have an overalllength of approximately eleven feet with a web width of approximatelyfive inches and a flange height of approximately two inches. Multipleenergy absorbing elements or rip plates 402, 404, 406, 408, 410 and 412and multiple spacers 416 and 418 are preferably attached to C-channels90 by threaded fasteners. For the example shown in FIG. 7, the samenumber and configuration of energy absorbing elements 402, 404, 406 ofvarious lengths and thicknesses are secured on opposite sides ofC-channels 90. For one application, energy absorbing elements 402, 404,406, 408, 410, and 412 were formed from galvanized mild steel plates.The number of energy absorbing elements, their thickness and location onthe exterior of energy absorbing assembly 486 is selected to provide thedesired deceleration characteristics for various sizes and types ofvehicles both during high speed and low speed impacts.

Spacers 416 and 418 are provided between energy absorbing elements 410and 412 on both sides of energy absorbing assembly 486. One of thetechnical benefits of the present invention includes the ability to varythe number, size and location of energy absorbing elements on each sideof an energy absorbing assembly to provide the desired decelerationcharacteristics.

Centerline slot 102 is preferably formed in energy absorbing elements402 and 404 immediately adjacent to the first end of energy absorbingassembly 486 to receive the associated cutter plate. For oneapplication, slot 102 is formed along the centerline of energy absorbingelements 402 and 404 with an opening of approximately one and one-halfinches tapering to a radius of approximately one-half inch in width overa length of approximately six inches. For some applications, energyabsorbing elements 402 and 404 may be replaceably secured with therespective supporting beams 90 by using relatively short mechanicalfastener 422. Also, the length of energy absorbing elements 402 and 404is relatively short in comparison with other energy absorbing elementswhich are attached to and form a part of energy absorbing assembly 486.The use of relatively short mechanical fasteners 422 and relativelyshort energy absorbing elements 402 and 404 allow energy absorbingassembly 486 to be quickly repaired and returned to service after arelatively minor impact. Mechanical fasteners 424, preferably extendfrom one side of energy absorbing assembly 486 to the other side ofenergy absorbing assembly 486. Mechanical fasteners 422 and 424 may bebolts or Hucks as previously described.

Energy absorbing elements 402, 404, 406, 408, 410 and 412 providestopping force that has been tailored for specific vehicle weights. Forexample, during approximately the first few feet of travel, of anassociated cutter plate through energy absorbing assembly 486, twostages of stopping force appropriate for a vehicle weighingapproximately 820 kilograms are provided. The remaining travel of acutter plate through energy absorbing assembly 486 provides stoppingforce that is appropriate for larger vehicles weighing approximately2,000 kilograms. Variations in the location, size, configuration andnumber of energy absorbing elements 402, 404, 406, 408, 410 and 412allows energy absorbing assembly 486 to provide safe deceleration ofvehicles weighing between 820 kilograms and 2,000 kilograms.

Energy absorbing element 200 as shown in FIG. 8 has been modified toreduce the initial effects of an impact between a moving vehicle and anenergy absorbing system incorporating teachings of the presentinvention, particularly with respect to lightweight vehicles. For someapplications, center line slot 202 at first end 201 of energy absorbingelement 200 may have a width of approximately three quarters of an inchand a length of approximately six inches. Slot 202 is used to receivecutter plate 206 during installation and to align cutter plate 206 withenergy absorbing elements 200. A plurality of elongated, oval slots 204are preferably formed along the center line of energy absorbing element200 extending from slot 202. For one application, oval slots 204 have alength of approximately two and one half (2½) inches and a width ofapproximately three quarters (¾) of an inch. The distance between thecenter line of adjacent oval slots 204 is approximately three inches.The number of oval slots 204 and the dimensions of oval slots 204 may bevaried depending upon the intended application for the associated energyabsorbing assembly. For one application, energy absorbing element 200has an overall length of forty-five (45) inches and a width of four andone half (4½) inches. Oval slots 204 reduce the energy required toinitiate ripping or tearing of energy absorbing element 200 on initialimpact particularly with respect to a lightweight vehicle. Oval slots204 cooperate with each other to substantially minimize the initialimpact or jolt experienced by a lightweight vehicle colliding with sledassembly 340.

For some applications, energy absorbing element 200 is preferablydisposed immediately adjacently to the respective cutter plate 106.Limiting the overall length of energy absorbing element 200 toapproximately forty-five (45) inches reduces the time and cost ofreturning energy absorbing system 20 or 320 to service following acollision by a lightweight vehicle or a slow speed vehicle with sledassembly 340, if repair is deemed appropriate. After a collision whichdid not require absorbing a substantial amount of energy, it may only benecessary to replace energy absorbing elements 200 and not all of theenergy absorbing elements which are attached to the associated energyabsorbing assembly 86.

Various types of mechanical fasteners may be satisfactorily used toreleasably attach energy absorbing elements 100, 200, and/or 402, 404,406, 408, 410 and 412 with the associated support beams 90. For someapplications, a combination of long bolts and short bolts may besatisfactorily used. For other applications, the mechanical fastenersmay be blind threaded rivets and associated nuts. A wide variety ofblind rivets, bolts and other fasteners may be satisfactorily used withthe present invention. Examples of such fasteners are available fromHuck International, Inc., located at 6 Thomas, Irvine, Calif.92718-2585. Power tools satisfactory for installing such blind rivetsare also available from Huck International and other vendors.

Energy absorbing system 20 incorporating teachings of the presentinvention is shown in FIGS. 9A, 9B and 10 installed adjacent to one endof roadside hazard 310 facing oncoming traffic. Energy absorbing system20 a incorporating a further embodiment of the present invention isshown in FIG. 9C. Energy absorbing systems 20 and 20 a may be formedfrom substantially the same components. Some of the differences betweenenergy absorbing system 20 and 20 a will be discussed later in moredetail. Energy absorbing systems 20 and 20 a may sometimes be describedas “nongating, redirective crash cushions.”

Portions of energy absorbing system 20 are shown in FIGS. 11-20. Variouscomponents and features of energy absorbing system 320 such as energyabsorbing assemblies 86, 186 and 486 and energy absorbing elements 100,152, 200, 402, 404, 406, 408, 410 and 412 may be incorporated intoenergy absorbing systems 20 and 20 a as desired. Energy absorbingsystems 20, 20 a and 320 dissipate kinetic energy by moving a cutterplate or cutter blade through respective energy absorbing elements whichremain in a generally fixed position relative to roadside hazard 310.

FIG. 9A is a schematic plan view showing energy absorbing system 20 inits first position, extending longitudinally from roadside hazard 310.Sled assembly 40 is slidably disposed at first end 21 of energyabsorbing system 20. Sled assembly 40 may sometimes be referred to as an“impact sled.”

First end 21 of energy absorbing system 20 including first end 41 ofsled assembly 40 faces oncoming traffic. Second end 22 of energyabsorbing system 20 is preferably securely attached to the end ofroadside hazard 310 facing oncoming traffic. Energy absorbing system 20is installed in its first position with first end 21 longitudinallyspaced from second end 22 as shown in FIG. 9A.

A plurality of panel support frames 60 a-60 e are spaced longitudinallyfrom each other and slidably disposed between first end 21 and secondend 22. The number of panel support frames may be varied depending uponthe desired length of the associated energy absorbing system. Panelsupport frames 60 a- 60 e may sometimes be referred to as “intermediateframes.”

Multiple panels 160 are respectively attached to sled assembly 40 andpanel support frames 60 a-60 e. Panels 160 may sometimes be referred toas “fenders” or “fender panels.”

When a vehicle impacts with first end 21 of energy absorbing system 20,sled assembly 40 will move longitudinally toward fixed roadside hazard310. Energy absorbing assemblies 186 (not expressly shown in FIGS. 9Aand 9B) will absorb energy from the impacting vehicle during thismovement. Panel support frames 60 a-60 e and associated panels 160 willalso absorb energy from a vehicle impacting first end 21. FIG. 9B is aschematic plan view which shows sled assembly 40 and panel supportframes 60 a-60 e and their associated panels 160 collapsed adjacently toeach other. Further longitudinal movement of sled assembly 40 towardroadside hazard 310 is prevented by panel support frames 60 a-60 e.

For purposes of explanation, the position of energy absorbing system 20as shown in FIG. 9B may be referred to as the “second” position. Duringmost vehicle collisions with end 21 of energy absorbing system 20, sledassembly 40 will generally move only a portion of the distance betweenthe first position as shown in FIG. 9A and the second position as shownin FIG. 9B.

Panel support frames 60 a-60 e, associated panels 160 and othercomponents of energy absorbing system 20 cooperate with each other toredirect vehicles striking either side of energy absorbing system 20back onto the associated roadway. Respective panels 160 are attached tosled assembly 40 and preferably extend over a portion of respectivepanels 160 attached to panel support frame 60 a. In a correspondingmanner, panels 160 attached to panel support frame 60 a preferablyextend over a corresponding portion of panels 160 attached to panelsupport frame 60 b.

First end 161 of each panel 160 is preferably securely attached to sledassembly 40 or panel support frame 60 a-60 d as appropriate. Each panel160 is also preferably slidably attached to one or more downstream panelsupport frames 60 a-60 e. Up stream panels 160 overlap down streampanels 160 to allow telescoping or nesting of respective panels 160 aspanel support frames 60 a-60 e slide toward each other. Subsets of panelsupport frames 60 a-60 e and panels 160 may be grouped together to forma one-bay group or a two-bay group. Various components of energyabsorbing system 20 provide substantial lateral support to panel supportframes 60 a-60 e and panels 160.

For purposes of illustration, second end 162 of each upstream panel 160is shown in FIGS. 9A and 9B projecting a substantial distance laterallyat the overlap with the associated downstream panel 160. As discussedlater in more detail, panels 160 incorporating teachings of the presentinvention will preferably nest closely with each other to minimize anylateral projection at second end 162 which might snag a vehicle during areverse angle impact with either side of energy absorbing system 20.

FIG. 9C is a schematic plan view showing energy absorbing system 20 a inits first position, extending longitudinally from roadside hazard 310.Energy absorbing system 20 a includes first end 21 facing oncomingtraffic and second end 22 securely attached to roadside hazard 310.Energy absorbing system 20 a also includes sled assembly 40, panelsupport frames 60 a-60 g and respective panels 160.

Panels 160 extending along both sides of energy absorbing systems 20 and20 a have substantially the same configuration. However, the length ofpanels 160 may vary depending on whether the respective panel 160 isused as a “one-bay panel” or for a “two-bay panel.” For purposes ofexplanation, a “bay” is defined as the distance between two adjacentpanels support frames.

The length of panels 160 designated as “two-bay panels” is selected tospan the distance between three-panel support frames when energyabsorbing systems 20 and 20 a are in their first position. For example,as discussed later in more detail, first end 161 of a two-bay panel 160is securely attached to an upstream panel support frame 60 a. Second end162 of two-bay panel 160 is slidably attached to a downstream panelsupport frame 60 c. Another panel support fame 60 b is slidably coupledwith two-bay panels 160 intermediate first end 161 and second end 162.

When sled assembly 40 hits panel support frame of a one-bay group(e-g.,panel support frame 60 c), the panel support frame and attached panels160 are accelerated toward the roadside hazard 310. The inertia of thepanel support frame and attached panels 160 contributes to thedeceleration of the impacting vehicle. If the panel support frame ofanother one-bay group is hit, the one-bay group will be coupled to itsown associated panels 160 and, therefore, will have relatively highinertia. To soften deceleration of an impacting vehicle, a two-bay groupis preferably disposed downstream from each one-bay group. When sledassembly 40, or one or more panel support frames being pushed by sledassembly 40, contacts the first panel support frame of a two-bay group(e.g., panel support frame 60 d), the inertia is the same or slightlymore than (because of the longer panels 160) the inertia of a one-baygroup. However, when the second panel support frame of the two-bay group(e.g., panel support frame 60 e) is contacted, the second panel supportframe 60 has a lower inertia because it is only slidably coupled to theassociated panels 160. Therefore, deceleration is somewhat reduced.

Energy absorbing system 20 a has the following groups of bays:2-2-1-2-2, where “2” means two bays and “1” means one bay. Beginning atsled assembly 40 and moving toward roadside hazard 310, energy absorbingsystem 20 a has a two-bay group (counting sled assembly 40 as a bay inand of itself), another two-bay group, a one-bay group, followed by atwo-bay group and another two-bay group.

As best shown in FIG. 10, nose cover 83 may be attached to sled assembly40 at first end 21 of energy absorbing system 20. Nose cover 83 may be agenerally rectangular sheet of flexible plastic type material. Oppositeedges of nose cover 83 are attached to corresponding opposite sides ofend 41 of sled assembly 40. End 41 of sled assembly 40 is normallylocated at first end 21 of energy absorbing system 20. Nose cover 83preferably includes a plurality of chevron delineators 84 which arevisible to oncoming traffic approaching roadside hazard 310. Varioustypes of reflectors and/or warning signs may also be mounted on sledassembly 40 and along each side of energy absorbing system 20.

Energy absorbing system 20 preferably includes multiple energy absorbingassemblies 186 aligned in respective rows 188 and 189 (See FIG. 20)extending generally longitudinally from fixed roadside hazard 310 andparallel with each other. For some applications, each row 188 and 189may contain two or more energy absorbing assemblies 186.

For the embodiment of the present invention as shown in FIG. 20, energyabsorbing assembly 186 in row 188 is spaced laterally from energyabsorbing assembly 186 in row 189. Rows 188 and 189 and/or energyabsorbing assemblies 186 may sometimes be referred to as a “guidancetrack” for sled assembly 40 and panel support frames 60 a-60 e.

An energy absorbing system incorporating teachings of the presentinvention may have energy absorbing assemblies arranged in variousconfigurations. For some applications, only a single row of energyabsorbing assemblies may be installed adjacent to roadside hazard 310.For other applications, three or more rows of energy absorbingassemblies may be installed. Also, each row may only have one energyabsorbing assembly or multiple energy absorbing assemblies.

As discussed later in more detail, energy absorbing assemblies 186 arepreferably securely attached to concrete foundation 308 in front ofroadside hazard 310. Each row 188 and 189 of energy absorbing assemblies186 has a respective first end 187 which corresponds generally withfirst end 21 of energy absorbing system 20. First end 41 of sledassembly 40 is preferably disposed adjacent to first end 187 of rows 188and 189 prior to a vehicle impact.

Ramp assembly 30 is preferably provided at end 21 of energy absorbingsystem 20 to prevent small vehicles or vehicles with low groundclearance from directly impacting first end 187 of rows 188 and 189. Iframp assembly 30 is not provided, a small vehicle or vehicle with lowground clearance may contact either or both first ends 187 andexperience severe deceleration with substantial damage to the vehicleand/or injury to occupants in the vehicle.

Various types of ramps and other structures may be provided to ensurethat a vehicle impacting end 21 of energy absorbing 20 will properlyengage sled assembly 40 and not directly contact first ends 187 of rows188 and 189. For the embodiment of the present invention as shown inFIGS. 10, 11, and 14, ramp assembly 30 includes a pair of ramps 32. Eachramp 32 preferably includes leg 34 with tapered surface 36 extendingtherefrom. Connectors 38 extend from leg 34 opposite from taperedsurface 36. As best shown in FIG. 14, connectors 38 allow each ramp 32to be securely engaged with respective energy absorbing assembly 186.

For some applications, leg 34 may have a height of approximately six andone-half inches. Other components associated with energy absorbingsystem 20 such as energy absorbing assemblies 186 and guide rails 208and 209 will preferably have a generally corresponding height. Limitingthe height of ramps 32 and energy absorbing assemblies 186 will allowsuch components to pass under a vehicle impacting with end 41 of sledassembly 40.

Tapered surfaces 36 may have a length of approximately thirteen andone-half inches. Tapered surfaces 36 may be formed by cutting astructural steel angle (not expressly shown) having nominal dimensionsof three inches by three inches by one-half inch thick into sectionswith appropriate lengths and angles. The sections of structural steelangle may be attached to respective legs 34 using welding techniquesand/or mechanical fasteners. Ramps 32 may also be referred to as “endshoes.”

For some applications, roadside hazard 310 and/or energy absorbingsystem 20 may be disposed on and attached to a suitable concretefoundation. For the embodiment shown in FIGS. 10, 13 and 15, concretefoundation 308 preferably extends both longitudinally and laterally fromroadside hazard 310. As best shown in FIGS. 13, 15, 16 and 20 energyabsorbing assemblies 186 are preferably disposed on and secured to aplurality of cross ties 24. Each cross tie 24 is preferably secured toconcrete foundation 308 using respective bolts 26. Various types ofmechanical fasteners in addition to bolts 26 may be satisfactorily usedto secure cross ties 24 with concrete foundation 308.

For the embodiment of the present invention as shown in FIGS. 10-20,cross ties 24 may be formed from structural steel strips having anominal width of three inches and a nominal thickness of one half inch.The length of each cross tie 24 may be approximately twenty-two inches.Three holes are preferably formed in each cross tie 24 to accommodatebolts 26. During a vehicle collision with either side of energyabsorbing system 20, cross ties 24 are placed in tension. The materialsused to form cross ties 24 and their associated configuration areselected to allow cross ties 24 to deform in response to tension fromsuch side impacts and to absorb energy from the impacting vehicle.

Energy absorbing assemblies 186 are similar to previously describedenergy absorbing assemblies 86. For example, see FIGS. 6, 13 and 15. Forpurposes of describing embodiments of the present invention as shown inFIGS. 9A-20, supporting beams 190 immediately adjacent to cross ties 24are designated 190 a. The respective supporting beams 190 disposedimmediately there above are designated 190 b. Supporting beams 190 a and190 b have substantially identical dimensions and configurations (SeeFIG. 13) including respective web 192 with grips or flanges 194 and 196extending therefrom. For the embodiment as shown in FIGS. 9A-20, fourcross ties 24 are preferably attached to web 192 of supporting beams 190a opposite from respective flanges 194 and 196. As a result, thegenerally C-shaped cross section of each supporting beam 190 a extendsaway from respective cross ties 24.

The number of cross ties 24 attached to each supporting beam 190 a maybe varied depending upon the intended use of the resulting energyabsorbing system. For energy absorbing system 20, two supporting beams190 a are spaced laterally from each other and attached to four crossties 24. Conventional welding techniques and/or mechanical fasteners(not expressly shown) may be used to attach supporting beams 190 a withcross ties 24.

A plurality of energy absorbing elements 152 is preferably attached torespective supporting beams 190 a and 190 b using mechanical fasteners198 a and 198 b. For some applications each energy absorbing element 152may have substantially the same configuration and dimensions. For otherapplications such as shown in FIG. 20 energy absorbing elements 152 a,152 b, 152 c, 152 d, 152 e and 152 f with varying lengths, widths, andthicknesses may be used to form energy absorbing assemblies 186.

A pair of guide rails or guide beams 208 and 209 are preferably attachedto and extend laterally from respective supporting beams 190 b. Guiderails 208 and 209 are preferably formed from structural steel angleshaving legs of equal width such as three inches by three inches and athickness of approximately one-half of an inch. Guide rails 208 and 209each have first leg 211 and second leg 212 which intersect each other atapproximately a ninety-degree angle. A plurality of holes (not expresslyshown) is preferably formed along the length of second leg 212 to allowattaching guide rails 208 and 209 with mechanical fasteners 198 b torespective supporting beams 190 b. Mechanical fasteners 198 b arepreferably longer than mechanical fasteners 198 a to accommodate guiderails 208 and 209 and longitudinal force causing sled assembly 40 tomove toward roadside hazard 310.

As shown in FIGS. 10, 11, 13 and 14, sled assembly 40 is slidablydisposed on guide rails 208 and 209. As best shown in FIGS. 15 and 16,panel support frames 60 a-60 e are also slidably disposed on guide rails208 and 209. For the embodiment of the present invention as shown inFIG. 10, the length of guide rails 208 and 209 is longer than the lengthof the associated rows 188 and 189 of energy absorbing assemblies 186.When energy absorbing system 20 is in its second position as shown inFIG. 9B, panel support frames 60 a-60 e are disposed immediatelyadjacently to each other which prevents further movement of sledassembly 40. Therefore, it is not necessary for rows 188 and 189 ofenergy absorbing assemblies 186 to have the same length as guide rails208 and 209.

For the embodiment of the present invention as represented by energyabsorbing system 20, sled assembly 40 has the general configuration ofan open sided box. See FIG. 12. The materials used to form sled assembly40 and their configuration are preferably selected to allow sledassembly 40 to remain intact after impact by a high speed vehicle. Firstend 41 of sled assembly 40 corresponds generally with first end 21 ofenergy absorbing system 20. End 41 may also be referred to as the“upstream” end of sled assembly 40. End 47 of sled assembly 40 isdisposed opposite from end 41. End 47 may also be referred to as the“downstream” end of sled assembly 40. Sled assembly 40 also includessides 48 and 49 which extend between ends 41 and 47. As shown in FIGS.11 and 13, sides 48 and 49 of sled assembly 40 are preferably covered bypanels 160. For purposes of illustration, panels 160 have been removedfrom side 48 in FIG. 12.

Sled assembly 40 is further defined by corner posts 42, 43, 44 and 45which extend generally vertically from guide rails 208 and 209. For theembodiment of the present invention as shown in FIGS. 10-14, cornerposts 42 and 43 may be formed from structural steel strips having awidth of approximately four inches, a thickness of approximately threequarters of an inch. Each corner post 42 and 43 has a length ofapproximately thirty-two inches. Tapered surface 46 is preferably formedon the end of each corner post 42 and 43 immediately adjacent to theground or concrete foundation 308. The dimensions and configuration oftapered surfaces 46 is preferably selected to minimize or eliminatecontact between concrete foundation 308 and respective ends of cornerposts 42 and 43 that might prevent smooth linear movement of sledassembly 40 along guide rails 208 and 209 toward roadside hazard 310.

Corner posts 44 and 45 may be formed from structural steel angles havinglegs of equal width such as two and one half inches by two and one halfinches and a thickness of approximately three-eighths of an inch. Cornerposts 44 and 45 preferably have a length of approximately twenty-nineinches. Various configurations of braces and supports may be used torigidly attach corner post 42, 43, 44 and 45 with each other to providethe desired structural strength for sled assembly 40.

For the embodiment of the present invention as shown in FIGS. 10-14, topbrace 141 preferably extends laterally between corner posts 42 and 43.Top brace 142 preferably extends laterally between corner posts 44 and45. A pair of top braces 148 and 149 extend longitudinally between topbraces 141 and 142 along respective sides 48 and 49 of sled assembly 40.Bottom brace 51 preferably extends laterally between corner post 42 andcorner post 43 immediately above guide rails 208 and 209. Another bottombrace 52 preferably extends laterally between corner post 44 and cornerpost 45 immediately above guide rails 208 and 209.

End 41 of sled assembly 40 also includes braces 146 and 147 extendingdiagonally between respective corner posts 42 and 43 and bottom brace51. Corner posts 42 and 43, top brace 141, bottom brace 51 and braces146 and 147 cooperate with each other to provide a very rigid, strongstructure at first end 41 of sled assembly 40. End 47 of sled assembly40 includes diagonal braces 143, 144 and 145 along with diagonal braces146 and 147 to provide additional structural support for sled assembly40.

The dimensions of end 41 of sled assembly 40 which are defined in partby corner posts 42 and 43, top brace 141 and bottom brace 51 areselected to catch or gather an impacting vehicle. During a collisionbetween a motor vehicle and first end 21 of energy absorbing assembly20, kinetic energy from the colliding vehicle is transferred from firstend 41 to other components of sled assembly 40. The dimensions andconfiguration of end 41 may also be selected to effectively transferkinetic energy even if a vehicle does not impact the center of first end41 or if a vehicle impacts end 41 at an angle other than parallel withthe longitudinal axis of energy absorbing system 20.

A pair of C-shaped channels 50 and 53 preferably extend diagonally fromtop brace 141 to bottom brace 52. Channels 50 and 53 are preferablyspaced laterally from each other and laterally from corner posts 42 and43 and corner posts 44 and 45. Guide assembly 54 is preferably attachedto the ends of channels 50 and 53 extending from bottom brace 52. Thelength of channels 50 and 53 is selected to ensure that guide assembly54 will contact web 192 of respective supporting beams 190 b.

Guide assembly 54 preferably includes plate 55. The end of channels 50and 53 extending from bottom brace 52 are attached to one side of plate55. A pair of guides 58 and 59 are preferably attached to and extendgenerally vertically from the opposite side of plate 55. Guides 58 and59 are disposed at an angle relative to each other and the center ofguide assembly 54 to assist in maintaining sled assembly 40 properlypositioned between rows 188 and 189 of energy absorbing assemblies 186.Plate 55 may sometime be referred to as a guide shoe or skid. Guides 58and 59 may sometimes be referred to as “diverters.”

Respective tabs 56 and 57 are attached to the bottom end of corner posts44 and 45 adjacent to energy absorbing assemblies 186. Tabs 56 and 57project laterally inward from respective corner posts 44 and 45 towardand under guide rails 208 and 209. Bottom brace 52 is preferably spacedfrom tabs 56 and 57 such that legs 211 of guide rails 208 and 209 may berespectively disposed between tabs 56 and 57 and bottom brace 52. Asbest shown in FIG. 13, tabs 56 and 57 cooperate with bottom brace 52 tosecurely maintain sled assembly 40 on guide rails 208 and 209 while atthe same time allowing sled assembly 40 to slide along guide rails 208and 209 toward roadside hazard 310. Tabs 56 and 57 are particularlyhelpful in preventing undesired lateral rotation of sled assembly 40 inresponse to a side impact.

Most impacts between a motor vehicle and end 41 of sled assembly 40 willgenerally occur at a location substantially above energy absorbingassemblies 186. As a result, vehicle impact with end 41 will generallyresult in applying a rotational moment to sled assembly 40 which forcesbottom brace 52 to bear down on the top of guide rails 208 and 209.

The dimensions of plate 55 and guides 58 and 59 are selected to becompatible with web 192 of channels 190. During a collision between amotor vehicle and end 41 of sled assembly 40, force from the vehicle istransferred from top brace 141 through channels 50 and 53 to bottombrace 52 and guide assembly 54. As a result, plate 55 will apply forceto supporting beams 190 b to maintain the desired orientation of sledassembly 40 relative to energy absorbing assemblies 186.

The inertia of sled assembly 40 and the friction associated with bottombrace 52 sliding over the top of guide rails 208 and 209 and thefriction caused by contact between plate 55 and the top of supportingbeams 190 b will contribute to deceleration of the impacting vehicle.

For the embodiment of the present invention as best shown in FIGS. 11,12 and 14 connectors 214 and 216 are attached to bottom brace 51opposite from cross braces 145 and 146. Connectors 214 and 216 arespaced laterally from each other to receive connector 220 which isattached to and extends from cutter plate 206. Connectors 222 and 224are also preferably attached to corner post 42 and extend laterallytherefrom. Corresponding connectors 222 and 224 are also attached tocorner post 43 and extend laterally therefrom. Connectors 222 are spacedfrom respective connectors 224 a distance corresponding generally withthe thickness of cutter plate 206. As best shown in FIG. 14, a pluralityof holes is provided in connectors 214, 216, 220, 222, 224 and cutterplate 206 to allow mechanical fasteners to securely attach cutter plate206 with sled assembly 40 adjacent to energy absorbing assemblies 186.

As best shown in FIGS. 12, 14 and 20 cutter plate 206 preferablyincludes two sets of beveled cutting edges or ripping edges 107 and 109.Sled assembly 40 is slidably disposed on guide rails 208 and 209 withcutting edges 107 and 109 aligned with first end 187 of energy absorbingassemblies 186. The thickness of cutter plate 206 and the gap or cuttingzone 154 between supporting beams 190 a and 190 b are selected to allowcutter plate 206 to fit between flanges 194 and 196 of supporting beams190 a and 190 b. Cutter plate 206 is located within slots 102 of energyabsorbing assemblies 186.

As best shown in FIG. 14, cutter plate 206 preferably includesrespective guide plates 268. A respective guide plate 268 is provided oneach side of cutter plate 206 for each supporting beam 190. The width ofeach guide plate 268 is selected to be compatible with the width of therespective supporting beam 190. The combined thickness of each cutterplate 206 along with respective guide plates 268 is selected to becompatible with gap or cutting zone 154 formed between respectivesupport beams 190. The thickness of cutting plate 206 is selected tocorrespond generally with the dimensions of gap 154. Each guide plate268 is preferably disposed within the generally C-shaped cross sectiondefined by web 192 and flanges 194 and 196 of the associated supportbeams 190. For some applications, gap or cutting zone 154 betweensupporting beams 190 a and 190 b may be approximately one inch (ortwenty-five millimeters) and the thickness of cutter plates 206 may beapproximately one half inch.

During a collision with end 21 of energy absorbing system 20, a vehiclewill experience a deceleration spike as momentum is transferred from thevehicle to sled assembly 40 which results in sled assembly 40 and thevehicle moving in unison with each other. The amount of deceleration dueto the momentum transfer is a function of the weight of sled assembly40, along with the weight and initial speed of the vehicle. As sledassembly 40 slides longitudinally toward roadside hazard 310, guideassembly 54 will contact respective supporting beams 190 b to maintainthe desired alignment between sled assembly 40 and energy absorbingassemblies 186 and cutter plates 206. Sled assembly 40 maintains cutterblade 206 in alignment with cutting zone 154.

As sled assembly 40 continues sliding toward roadside hazard 310, cutterplate 206 will engage and separate energy absorbing elements 152 of therespective energy absorbing assemblies 186. When sled assembly 40 isimpacted by a vehicle, cutter plate 206 is pushed into the edge of eachenergy absorbing element 152. Beveled edges 107 and 109 of cutter plate206 engage the respective energy absorbing elements 152. Cutter plate206 may be formed from various steel alloys. Beveled edges 107 and 109are preferably hardened to provide desired cutting and/or ripping ofenergy absorbing elements 152.

The center portion of each energy absorbing element 152 is forcedinwardly between respective supporting beams 190, while the top andbottom portions of each energy absorbing element 152 are fixed torespective supporting beams 190 by bolts 198 a and 198 b. The centerportion of each energy absorbing clement 152 continues to be stretchedor deformed by cutter plate 206 until the respective energy absorbingelement 152 typically fails in tension This creates a separation in eachenergy absorbing element 152 which propagates along the length ofrespective energy absorbing elements 152 as sled assembly 40 continuesto be push cutter plate 206 therethrough.

The separation of energy absorbing elements 152 will stop when kineticenergy from the impacting vehicle has been absorbed. After the passageof cutter plate 206, one or more energy absorbing elements 152 will beseparated into upper and lower parts (See FIG. 5), which upper and lowerparts are separated by a gap.

Cutter plate 206, when viewed from associated energy absorbing elements152, has the configuration of a deep, strong beam. Cutter plate 206 issecured to sled assembly 40 at both ends and in the center and istherefore rigid. Thus, when cutter plate 206 engages energy absorbingelements 152, the energy absorbing elements 152 fails while cutter plate206 does not.

As previously noted, the thickness and number of energy absorbingelements 152 may be varied to safely absorb the kinetic energy from awide range of vehicle types, sizes and/or speeds of impact. Therotational moment which is generally applied to end 41 of sled assembly40 will also increase frictional forces between cutter plate 206 andportions of energy absorbing element 152 which have been sheared orripped.

For the embodiment as shown in FIG. 9A, end 47 of sled assembly 40 willcontact panel support frame 60 a which will, in turn, contact panelsupport frame 60 b and any other panel support frames disposeddownstream from sled assembly 40. Movement of sled assembly 40 towardroadside hazard 310 results in telescoping of panel support frames andtheir associated panels 160 with respect to each other. The inertia ofpanel support frames and their associated panels 160 will furtherdecelerate an impacting vehicle as sled assembly 40 moves longitudinallyfrom first end 21 toward second end 22 of energy absorbing system 20.The telescoping or sliding of panels 160 against one another producesadditional friction forces which also contribute to deceleration of thevehicle. Movement of panel support frames along guide rails 208 and 209also produces additional frictional forces to even further deceleratethe vehicle.

As previously discussed with respect to FIGS. 9A and 9B, panel supportframes 60 a-60 e and associated panels 160 will redirect vehiclesstriking either side of energy absorbing system 20 back onto theassociated roadway. Each panel 160 preferably has a generally elongatedrectangular configuration defined in part by first end or upstream end161 and second end or downstream end 162. (See FIGS. 9A, 10 and 17.)Each panel 160 preferably includes first edge 181 and second edge 182which extend longitudinally between first end 161 and second end 162.(See FIGS. 10, 17 and 18.) For some applications panels 160 may beformed from standard ten (10) gauge W beam guardrail sections having alength of approximately thirty-four and three-fourth inches for “one-baypanels” and five feet two inches for “two-bay panels.” Each panel 160preferably has approximately the same width of twelve and one-fourthinches.

As shown in FIGS. 16 and 17, slot 164 is preferably formed in each panel160 intermediate ends 161 and 162. Slot 164 is preferably aligned withand extends along the longitudinal center line (not expressly shown) ofeach panel 160. The length of slot 164 is less than the length of theassociated panel 160. A respective slot plate 170 is slidably disposedin each slot 164.

Metal strap 166 is preferably welded to first end 161 of each panel 160along edges 181 and 182 and the middle. For some applications metalstrap 166 may have a length of approximately twelve and one-fourthinches and a width of approximately two and one-half inches. The lengthof each metal strap 166 is preferable equal to the width of therespective panel 160 extends between respective longitudinal edges 181and 182.

Mechanical fasteners 167, 168, and 169 may be used to attach each metalstrap 166 with its associated corner post 68 or 69. Mechanical fasteners167 and 169 are substantially identical. Metal straps 166 provide morecontact points for mounting end 161 of panels 160 to respective panelsupport frames 60 a-60 f.

Recesses 184 are preferably formed in each panel 160 at the junctionbetween second end 162 and respective longitudinal edges 181 and 182.(See FIG. 17) Recesses 184 allow panels 160 to fit with each other in atight overlapping arrangement when energy absorbing system 20 is in itsfirst position. As a result, recesses 184 minimize the possibility of avehicle snagging the sides of energy absorbing system 20 during a“reverse angle” collision or impact.

Panel support frames 60 a-60 e have substantially the same dimensionsand configuration. Therefore, only panel support fame 60 e as shown inFIG. 16 will be described in detail. Panel support frame 60 e has agenerally rectangular configuration defined in part by first post 68disposed adjacent to guide rail 208 and second post 69 disposed adjacentto guide rail 209. Top brace 61 extends laterally between first post 68and second post 69. Bottom brace 62 extends laterally between first post68 and second post 69. The length of posts 68 and 69 and the location ofbottom brace 62 are selected such that when panel support frame 60 e isdisposed on guide rails 208 and 209, bottom brace 62 will contact guiderails 208 and 209 but posts 68 and 69 will not contact concretefoundation 308.

A plurality of cross braces 63, 64, 65, 70 and 71 may be disposedbetween posts 68 and 69, top brace 61 and bottom brace 62 to provide arigid structure. For some applications cross braces 63, 64, 65, 70 and71 and/or posts 68 and 69 may be formed from relatively heavy structuralsteel components. Also, cross brace 65 may be installed at a lowerposition on posts 68 and 69. The weight of support frames 60 a-60 e andthe location of the associated cross braces to provide desired strengthduring a side impact with energy absorbing system 20.

Tab 66 (See FIG. 15) is attached to the end of post 69 adjacent toconcrete foundation 308 and extends laterally toward energy absorbingassemblies 186. Tab 67 is attached to the end of post 68 adjacent toconcrete assembly 308 and extends laterally toward energy absorbingassemblies 186. Tabs 66 and 67 cooperate with bottom brace 62 tomaintain panel supporting frame 60 e engaged with guide rails 208 and209 during a side impact with energy absorbing system 20 to prevent orminimize rotation in a direction perpendicular to guide rails 208 and209 while allowing panel supporting frame 60 e to slide longitudinallytoward roadside hazard 310.

Impact from a vehicle colliding with either side of energy absorbingassembly 20 will be transferred from panels 160 to panel support frames60 a-60 g. The force of the lateral impact will then be transferred frompanel support frames 60 a-60 g to the associated guide rails 208 and/or209 to energy absorbing assemblies 186 through cross ties 24 andmechanical fasteners 26 to concrete foundation 308. Cross ties 24,mechanical fasteners 26, energy absorbing assemblies 186, guide rails208 and 209 along with panel support frames 60 a-60 g provides lateralsupport during a side impact with energy absorbing, system 20.

For purposes of explanation, panels 160 shown in FIGS. 17 and 18 havebeen designated 160 a, 160 b, 160 c, 160 d, 160 e and 160 f. Further,the longitudinal edges of panels 160 a-160 d are identified aslongitudinal edges 18la-181 d and 182 a-182 d, and the longitudinaledges of panel 160 f are identified as longitudinal edges 181 f and 182f. Also, for panels 160 a, 160 b, and 160 d, ends 161 and 162 areidentified as ends 161 a and 162 a, ends 161 b and 162 b, and ends 161 dand 162 d, respectively. Likewise, for panel 160 c, the upstream end isidentified as end 161 c; and for panel 160 e, the downstream end isidentified as end 162 e. For the embodiment of the present invention, asshown in FIG. 17, respective metal straps 166 are provided to attachfirst end 161 a and first end 161 d to post 68 of panel support frame 60c. In a similar manner, respective metal straps 166 are provided tosecurely attach first end 161 b and 161 e to corner post 68 of panelsupport frame 60 d. As best shown in FIG. 18, bolt 168 extends throughhole 172 in respective slot plate 170 and a corresponding hole (notexpressly shown) in panel 160 b.

As best shown in FIG. 19, slot plate 170 preferably includes hole 172extending therethrough. A pair of fingers 174 and 176 extend laterallyfrom one side of slot plate 170. Fingers 174 and 176 are sized to bereceived within slot 164 of the associated panel 160. Mechanicalfastener 168 is preferably longer than mechanical fasteners 167 and 169to accommodate slot plate 170. Each slot plate 170 and bolt 168cooperate with each other to securely anchor end 161 of an inner panel160 with the associate post 68 or 69 while allowing an outer panel 160to slide longitudinally relative to the associated post 68 or 69. Seeinner panel 160 b and outer panel 160 a in FIG. 18.

For the embodiment of the present invention as shown in FIGS. 17 and 18,a portion of bolt 168 along with associated fingers 174 and 176 of slotplate 170 are slidably disposed in longitudinal slot 164 of panel 160 b.During a vehicle impact with end 21 of energy absorbing assembly 20,panel support frame 60 c with first end 161 a of panel 160 a will movelongitudinally toward roadside hazard 310. The engagement of theassociated slot plate 170 within longitudinal slot 164 will allow panel160 a to slide longitudinally relative to panel 160 b until panelsupport frame 60 c contacts panel support frame 60 d. When this contactoccurs, panel support frame 60 d and associated panels 160 will movewith panel support frame 60 c and its associated panels 160 towardroadside hazard 160.

Upon a vehicle impact with the sled assembly 40, sled assembly 40 ispushed into the frames which are maintained in vertical alignment byguide rails 208 and 209, bottom brace 62 and tabs 66 and 67 as theframes slide toward roadside hazard 310.

As previously discussed each panel support frame 60 a-60 e is slidablydisposed on guide rails 208 and 209. As best shown in FIG. 17, upstreampanel 160 b overlaps downstream panel 160 c. End 161 c of downstreampanel 160 c is preferably welded to strap 166. Slot plate 170 isslidably disposed in slot 164 of upstream panel of 160 b. Therefore, aspanel support frame 60 d moves longitudinally toward panel support frame60 e, panel 160 b may slide longitudinally and telescope over downstreampanel 160 c.

For many applications, energy absorbing elements disposed immediatelyadjacently to sled assembly 40 will typically be relatively thin or“soft” to decelerate relatively small, slow-moving vehicles. The lengthof energy absorbing system 20 is preferably selected to be long enoughto provide for multiple stages for satisfactory deceleration of large,high-speed vehicles after sled assembly 40 has moved through the frontportion with “relatively soft” energy absorbing elements. Generally,energy absorbing elements installed in the middle portion of energyabsorbing system 20 and immediately adjacent to roadside hazard 310 willbe relatively “hard” as compared to energy absorbing elements installedadjacent to first end 21.

When a vehicle initially impacts end 21 of energy absorbing system 20,any occupants who are not wearing a seat belt or other restrainingdevice will be catapulted forward from their seat. Properly restrainedoccupants will generally decelerate with the vehicle. During the shorttime period and distance sled assembly 40 travels along guide rails 208and 209, an unrestrained occupant may be airborne inside the vehicle.Deceleration forces applied to the impacting vehicle during this sametime period may be quite large. However, just prior to an unrestrainedoccupant contacting interior portions of the vehicle, such as thewindshield (not expressly shown), deceleration forces applied to thevehicle will preferably be reduced to lower levels to minimize possibleinjury to the unrestrained occupant.

The relative “softness” or “hardness” of energy absorbing system 20 isdetermined by the number and characteristics of energy absorbingelements 152, the location of energy absorbing elements 152, and thelocation and inertia associated with panel support frames 60 a-60 g andtheir associated panels 160. For example, energy absorbing element 200shown in FIG. 8 may be modified to be relatively hard by reducing thenumber and/or size of oval slot 204. In the same manner, energyabsorbing element 200 may be made relatively soft by increasing thenumber and/or site of oval slot 204. Increasing the thickness of energyabsorbing elements 152 will increase the amount of force required topush cutter plate 206 therethrough and thus, produces a harder portionin the associated energy absorbing system 20. Energy absorbing assembly486 as previously described in FIG. 7 shows various techniques forincreasing the hardness of an energy absorbing system. Thus, the presentinvention allows modifying energy absorbing system 20 to minimizepossible injury to both restrained and unrestrained occupants in a widevariety of vehicles traveling at various speeds.

Energy absorbing system 20 as shown in FIG. 20 preferably includesenergy absorbing elements 152 a, 152 b, 152 c, 152 d, 152 e and 152 f.Energy absorbing elements 152 a and 152 b are preferably formed fromrelatively thin sixteen gauge construction steel strips having a nominalwidth of four and one half inches. Energy absorbing element 152 apreferably has a nominal length of approximately fifty-four inches.Energy absorbing element 152 b preferably has a nominal length ofapproximately sixty inches. Energy absorbing elements 152 c and 152 dare preferably formed from structural steel strips having a nominalwidth of four and one half inches and thickness of three-sixteenths ofan inch. Energy absorbing element 152 c preferably has a nominal lengthof approximately seventy-six inches. Energy absorbing element 152 dpreferably has a nominal length of approximately seventy inches. Energyabsorbing elements 152 e are preferably formed from the same type ofmaterial. Energy absorbing elements 152 f are preferably formed fromstructural steel strips having a width of approximately four andone-half inches and a length of approximately ninety-two inches. Eachenergy absorbing element 152 f preferably has a thickness correspondingwith ten gauge construction steel strips.

By combining energy absorbing elements 152 a, 152 b, 152 c, 152 d, 152 eand 152 f, as shown in FIG. 20, energy absorbing assemblies 186 willhave a relatively “soft” first portion, a “hard” middle portion and a“harder” final portion adjacent to roadside hazard 310. Energy absorbingelements 152 a, 152 b, 152 c, 152 d, 152 e and 152 f are staggered todecrease the change in deceleration forces applied to an impactingvehicle as cutter blade 206 passes from the first portion of energyabsorbing assembly 220 to the middle portion of energy absorbing system20.

When sled assembly 40 hits thicker energy absorbing media, such as thepreviously described energy absorbing elements, sled assembly 40 slowsdown while the panel support frames continue to slide toward fixedhazard 310, telescoping panels 160 along the way. Thus, the panelsupport frames will typically move out of the way so that they no longercontribute to deceleration of the vehicle.

If the sled assembly 40 is hit at an angle, energy absorbing system 20will generally function as previously described to decelerate theimpacting vehicle. Depending upon the angle of impact with sled assembly40, additional deceleration may occur due to increased friction forcesbeing applied to sled assembly 40 as it slides along guide rails 208 and209.

If panels 160 are hit, the vehicle is redirected back to the roadway andaway from the fixed hazard. The impact is transmitted from the panels160 to respective panel support frames. The panel support frames attemptto rotate, as panels 160 are usually hit high. However, the panelsupport frames are prevented from rotating on guide rails 208 and 209 byinwardly extending projections 56 and 57 underneath beam guides on therails. Thus, the system “gives” when hit on its side by allowing thecross-ties to deform. Much like the system's collapse during a head oncollision, this “give” on a lateral impact reduces deceleration forcesapplied to a side impacting vehicle. The system remains in place after alateral redirecting impact.

End weldment 242 is preferably provided at end 22 of energy absorbingsystem 20 for use in attaching energy absorbing system 20 with the endof roadside hazard 310 facing oncoming traffic. For some applicationsend weldment 242 has substantially the same configuration as panelsupporting frames 60 a-60 g.

What is claimed is:
 1. An energy absorbing system to minimize theresults of a collision between a vehicle traveling on a roadway and aroadside hazard comprising: the energy absorbing system having a firstend and a second end; the second end of the energy absorbing systemdisposed adjacent to the roadside hazard with the first end extendinglongitudinally therefrom; a sled assembly slidably disposed at the firstend of the energy absorbing system; at least one energy absorbingassembly disposed between the roadside hazard and the sled assembly;each energy absorbing assembly having at least one energy absorbingelement; the sled assembly having a cutter plate mounted adjacent to andaligned with each energy absorbing element; and the sled assembly havinga first end facing oncoming traffic whereby a collision of a vehiclewith the first end of the sled assembly will cause the cutter plate toslide longitudinally relative to the energy absorbing element anddissipate kinetic energy of the vehicle by separating the energyabsorbing element.
 2. The energy absorbing system of claim 1 furthercomprising: a pair of energy absorbing assemblies extendinglongitudinally from the roadside hazard and spaced laterally from eachother; and the cutter plate having two sets of cutter blades with oneset of cutter blades disposed adjacent to and aligned with one energyabsorbing assembly and the other set of cutter blades disposed adjacentto and aligned with the other energy absorbing assembly.
 3. The energyabsorbing system of claim 1 further comprising: a first row of energyabsorbing assemblies and a second row of energy absorbing assembliesextending longitudinally from the roadside hazard; the first row and thesecond row of energy absorbing assemblies spaced laterally from eachother; and the cutter plate having a first set of cutter blades and asecond set of cutter blades with the first set of cutter blades alignedwith the first row of energy absorbing assemblies and the second set ofcutter blades aligned with the second row of energy absorbingassemblies.
 4. The energy absorbing system of claim 1 furthercomprising: a first row of energy absorbing assemblies and a second rowof energy absorbing assemblies extending longitudinally from theroadside hazard; the first row and the second row of energy absorbingassemblies spaced laterally from each other; and the sled assemblyhaving a guide assembly attached to and extending therefrom forengagement with the first row and the second row of energy absorbingassemblies.
 5. The energy absorbing system of claim 1 furthercomprising: a pair of energy absorbing assemblies spaced laterally fromeach other; the sled assembly slidably coupled to one end of each energyabsorbing assembly; each energy absorbing assembly further comprising atleast one energy absorbing element; and the cutter plate having two setsof cutter blades disposed adjacent to respective energy absorbingassemblies whereby the collision between the vehicle and the sledassembly will result in the cutter plate separating at least onerespective energy absorbing element to dissipate energy from thecollision of the vehicle.
 6. The energy absorbing system of claim 1further comprising: a first row of energy absorbing assemblies and asecond row of energy absorbing assemblies extending longitudinally fromthe roadside hazard; the first row and the second row of energyabsorbing assemblies spaced laterally from each other; a first guiderail attached to and extending laterally from the first row of energyabsorbing assemblies; and a second guide rail attached to and extendinglaterally from the second row of energy absorbing assemblies.
 7. Theenergy absorbing system of claim 1 wherein each energy absorbingassembly further comprises: a pair of supporting beams disposedlongitudinally parallel with each other; the supporting beams spacedfrom each other; a pair of energy absorbing elements attachedrespectively to opposite sides of each supporting beam; and the distancebetween the supporting beams selected to allow the cutter plate to ripeach energy absorbing element to dissipate energy from the impact by thevehicle.
 8. The energy absorbing system of claim 1 further comprising:the cutter plate attached to the sled assembly; at least one energyabsorbing assembly having a plurality of energy absorbing elementsattached thereto with the sled assembly slidably coupled to one end ofthe energy absorbing assembly; the plurality of energy absorbingelements aligned with the cutter plate; and the energy absorbingelements having a variation in thickness along the length of the energyabsorbing assembly whereby an increasing amount of force is required tomove the cutter plate through the energy absorbing elements.
 9. Anenergy absorbing system to minimize the results of a collision between avehicle traveling on a roadway and a roadside hazard comprising: theenergy absorbing system having a first end and a second end; the secondend of the energy absorbing system disposed adjacent to the roadsidehazard with the first end extending longitudinally therefrom; a sledassembly slidably disposed at the first end of the energy absorbingsystem; a first row of energy absorbing assemblies and a second row ofenergy absorbing assemblies extending longitudinally from the roadsidehazard, at least one of the energy absorbing assemblies among the firstrow and the second row of energy absorbing assemblies being disposedbetween the roadside hazard and the sled assembly, the first row and thesecond row of energy absorbing assemblies spaced laterally from eachother; each energy absorbing assembly having at least one energyabsorbing element; the sled assembly having a cutter plate mountedadjacent to and aligned with each energy absorbing element; the sledassembly having a first end facing oncoming traffic whereby a collisionof a vehicle with the first end of the sled assembly will cause thecutter plate to slide longitudinally relative to the energy absorbingelement and dissipate kinetic energy of the vehicle by separating theenergy absorbing element; a plurality of panel support frames slidablydisposed on the first guide rail and the second guide rail between thesled assembly and the roadside hazard; the panel support frames spacedlongitudinally from each other; and a plurality of panels attached tothe panel support frames and extending longitudinally along oppositesides of the energy absorbing system.
 10. A crash cushion to minimizethe results of a collision between a vehicle traveling on a roadway andan immobile roadside hazard comprising: a pair of energy absorbingassemblies extending longitudinally parallel with each other; the energyabsorbing assemblies spaced laterally from each other; the energyabsorbing assemblies having a first end facing oncoming traffic and asecond end disposed adjacent to the roadside hazard; a sled assemblyslidably coupled to the first end of each energy absorbing assembly;each energy absorbing assembly having at least one energy absorbingelement; and a cutter plate attached to the sled assembly adjacent toand aligned respectively with the energy absorbing assemblies whereby acollision of the vehicle with the sled assembly will result in thecutter plate sliding longitudinally relative to the respective energyabsorbing elements and separating the respective energy absorbingelements to dissipate kinetic energy from the vehicle.
 11. The crashcushion of claim 10 wherein each energy absorbing assembly furthercomprises: a pair of supporting beams disposed longitudinally parallelwith each other; the supporting beams spaced from each other; at leasttwo energy absorbing elements attached to opposite sides of eachsupporting beam; and the distance between the supporting beams selectedto allow the respective cutter plate to separate the respective energyabsorbing elements to dissipate energy from the vehicle collision. 12.The crash cushion of claim 10 further comprising: the pair of energyabsorbing assemblies spaced laterally from each other and extendinglongitudinally parallel with each other between the sled assembly andthe roadway hazard; a plurality of cross braces extending between theenergy absorbing assemblies whereby the energy absorbing assemblies andcross braces cooperate with each other to form a rigid frame structure;and the cutter plate attached to the sled assembly adjacent to therespective energy absorbing assemblies.
 13. The crash cushion of claim10 wherein each energy absorbing assembly further comprises: twosupporting beams extending longitudinally parallel with each other; thesupporting beams spaced from each other; at least one energy absorbingelement attached to each supporting beam; at least one cutter plateattached to the sled assembly adjacent to one end of the energyabsorbing element; and the distance between the supporting beamsselected to allow the respective cutter plate to rip the portion of theenergy absorbing element between the respective supporting beams todissipate energy from the vehicle collision.
 14. The crash cushion ofclaim 10 further comprising: the cutter plate having two sets of cutterblades; and each energy absorbing assembly having at least two energyabsorbing elements with each set of cutter blades disposed at an acuteangle relative to respective energy absorbing elements.
 15. The crashcushion of claim 10 wherein each energy absorbing assembly furthercomprises: a pair of supporting beams disposed longitudinally parallelwith each other; the supporting beams spaced from each other; aplurality of energy absorbing elements attached to one side of eachsupporting beam; a plurality of energy absorbing elements attached tothe opposite side of each supporting beam; and a spacer disposed betweenselected energy absorbing elements.
 16. A crash cushion to minimize theresults of a collision between a vehicle traveling on a roadway and animmobile roadside hazard comprising: a pair of energy absorbingassemblies extending longitudinally parallel with each other; the energyabsorbing assemblies spaced laterally from each other; the energyabsorbing assemblies having a first end facing oncoming traffic and asecond end disposed adjacent to the roadside hazard; each energyabsorbing assembly having at least one energy absorbing element; a pairof guide rails with each guide rail attached to and extending laterallyfrom one of the energy absorbing assemblies; a sled assembly slidablycoupled to the first end of each energy absorbing assembly, the sledassembly being disposed on and secured to the guide rails; a pluralityof panel support frames slidably disposed on the guide rails between thesled assembly and the roadside hazard; a plurality of panels attached tothe panel support frames; and a cutter plate attached to the sledassembly adjacent to and aligned respectively with the energy absorbingassemblies whereby a collision of the vehicle with the sled assemblywill result in the cutter plate sliding longitudinally relative to therespective energy absorbing elements and separating the respectiveenergy absorbing elements to dissipate kinetic energy from the vehicle.17. A crash cushion to minimize the results of a collision between avehicle traveling on a roadway and an immobile roadside hazardcomprising: a pair of energy absorbing assemblies extendinglongitudinally parallel with each other; the energy absorbing assembliesspaced laterally from each other; the energy absorbing assemblies havinga first end facing oncoming traffic and a second end disposed adjacentto the roadside hazard; each energy absorbing assembly having: a pair ofsupporting beams disposed longitudinally parallel with each other; thesupporting beams spaced from each other; at least two energy absorbingelements attached to opposite sides of each supporting beam; thedistance between the supporting beams selected to allow the respectivecutter plate to separate the respective energy absorbing elements todissipate energy from the vehicle collision; each supporting beam havinga generally C-shaped cross section; the energy absorbing elementsattached to opposite sides of each supporting beam with the generallyC-shaped cross sections of the respective supporting beams facing eachother to define a generally hollow rectangular cross section for theresulting energy absorbing assembly; and each energy absorbing elementattached to the respective supporting beams by releasable fasteners toallow replacement of the energy absorbing element; a sled assemblyslidably coupled to the first end of each energy absorbing assembly; anda cutter plate attached to the sled assembly adjacent to and alignedrespectively with the energy absorbing assemblies whereby a collision ofthe vehicle with the sled assembly will result in the cutter platesliding longitudinally relative to the respective energy absorbingelements and separating the respective energy absorbing elements todissipate kinetic energy from the vehicle.
 18. A method to minimize theeffects of a collision between a motor vehicle traveling on a roadwayand a roadway hazard comprising the steps of: forming at least oneenergy absorbing assembly from a pair of supporting beams; attaching atleast one energy absorbing element to the supporting beams; installingthe energy absorbing assembly adjacent to the roadway hazard with oneend of the energy absorbing assembly facing on-coming traffic; forming asled assembly with a cutter plate attached thereto; and slidablycoupling the sled assembly with the one end of the energy absorbingassembly and the cutter plate disposed adjacent to the energy absorbingelement whereby a collision between the motor vehicle and the sledassembly will result in the cutter plate sliding longitudinally relativeto the energy absorbing element and separating the energy absorbingelement to dissipate energy from the collision by the motor vehicle. 19.A method to minimize the effects of a collision between a motor vehicletraveling on a roadway and a roadway hazard comprising the steps of:forming at least one energy absorbing assembly from a pair of supportingbeams, at least one of the support beams having a generally C-shapedcross section; attaching at least one energy absorbing element to thesupporting beams; installing the energy absorbing assembly adjacent tothe roadway hazard with one end of the energy absorbing assembly facingon-coming traffic; forming a sled assembly with a cutter plate attachedthereto; slidably coupling the sled assembly with the one end of theenergy absorbing assembly and the cutter plate disposed adjacent to theenergy absorbing element; attaching a guide plate to at least one sideof the cutter plate; and placing the guide plate within the C-shapedcross section to maintain alignment of the cutter plate assembly withthe respective energy absorbing assembly, whereby a collision betweenthe motor vehicle and the sled assembly will result in the cutter platesliding longitudinally relative to the energy absorbing element andseparating the energy absorbing element to dissipate energy from thecollision by the motor vehicle.
 20. An energy absorbing system tominimize the results of a collision between a vehicle and a roadsidehazard comprising: a first end and a second end, with the second enddisposed adjacent to the roadside hazard and the first end positioned adistance away from the roadside hazard, such that the energy absorbingsystem extends longitudinally from the roadside hazard in a firstdirection toward oncoming traffic; an impact-receiving structuredisposed at the first end; an energy absorbing element disposedlongitudinally in the first direction between the roadside hazard andthe impact-receiving structure; and at least one contact surface on theimpact-receiving structure engagable with the energy absorbing element,such that kinetic energy from the collision is dissipated by splittingthe energy absorbing element with a tensile force.
 21. The energyabsorbing system of claim 20, wherein the at least one contact surfaceengages the energy absorbing element at an acute angle, relative to thelongitudinal disposition of the energy absorbing element.
 22. The energyabsorbing system of claim 21, wherein the at least one contact surfaceengages the energy absorbing element at an angle of approximatelyforty-five degrees, relative to the longitudinal disposition of theenergy absorbing element.
 23. The energy absorbing system of claim 20,wherein the at least one contact surface is forced longitudinallythrough the energy absorbing element when the impact-receiving structureis impacted by a vehicle.
 24. An energy absorbing system to minimize theresults of a collision between a vehicle and a roadside hazardcomprising: a first end and a second end, with the second end disposedadjacent to the roadside hazard and the first end positioned a distanceaway from the roadside hazard, such that the energy absorbing systemextends longitudinally from the roadside hazard in a first directiontoward oncoming traffic; an impact-receiving structure disposed at thefirst end; an energy absorbing element disposed longitudinally in thefirst direction between the roadside hazard and the impact-receivingstructure; and a splitter with at least one contact surface that engagesthe energy absorbing element and dissipates kinetic energy from thecollision by splitting the energy absorbing element with a tensile forcewhen the impact-receiving structure is impacted by a vehicle.
 25. Theenergy absorbing system of claim 24, wherein the splitter is forcedlongitudinally through the energy absorbing element when theimpact-receiving structure is impacted by a vehicle.
 26. The energyabsorbing system of claim 24, wherein the at least one contact surfaceengages the energy absorbing element at an acute angle, relative to thelongitudinal disposition of the energy absorbing element.
 27. The energyabsorbing system of claim 24, wherein the energy absorbing elementcomprises a length of metal.
 28. A method of installing a crash cushionthat minimiizes the results of a collision between a vehicle and a fixedobstacle, comprising the steps of: providing a track from the obstacleto a position some distance away, the track having a first end at theposition and a second end adjacent to the obstacle, the track beingoriented so as to be parallel to a direction of vehicle traffic passingnear the obstacle; mounting a rip medium to ground, the rip mediumextending from the first end toward the second end; providing a carriagehaving a cutter mounted thereto; mounting the carriage to the track atthe first end and aligning the cutter so as to engage the rip mediumwhen the carriage is pushed toward the obstacle; positioning pluralframes on the track between the first and second ends, the frames beingspaced apart from each other; and coupling panels to the frames, witheach panel extending between two or more frames.
 29. The method of claim28 wherein the step of coupling the panels to the frames furthercomprises overlapping the panels so that the panels nest when the panelsare forced toward the second end.
 30. A crash cushion to minimize theresults of a collision between a vehicle and a fixed obstacle,comprising: a first and a second end with the second end of the crashcushion disposed adjacent to the fixed obstacle and the first end of thecrash cushion extending longitudinally therefrom; a failure mediumextending in a first direction and having first and second ends, thefailure medium having two edge portions and a center portion locatedbetween the two edge portions, the two edge portions and the centerportion extending in the first direction; a support extending in thefirst direction and being coupled to the failure medium along the twoedge portions, with the center portion being free to deform; a sledassembly slidably disposed at the first end of the failure medium; thefailure medium disposed between the fixed obstacle and the sledassembly; a cutter mounted the sled assembly; a track extending betweenthe first and second ends, the sled assembly being moveably mounted onthe track, the track being oriented so as to allow the cutter to movelongitudinally through the failure medium center portion between thefirst and second ends by the cutter deforming the center portion andcausing the center portion to fail in tension.
 31. The crash cushion ofclaim 30 wherein the failure medium comprises one or more metal plates.32. The crash cushion of claim 31 wherein the failure medium plate has athickness, the cutter being oriented so as to traverse through the platein an orientation having a parallel component to the plate thickness.33. The crash cushion of claim 31 wherein the cutter has an edge thatengages the failure medium plate, the edge being oriented at an anglerelative to the first direction.
 34. The crash cushion of claim 30wherein the support forms a channel extending in the first direction,the failure medium center portion spanning at least a portion of thechannel, the channel receiving the cutter.
 35. The crash cushion ofclaim 30 wherein the support comprises the track.
 36. The crash cushionof claim 30 wherein the carriage has a guide that slidably engages thetrack.
 37. The crash cushion of claim 30 wherein the failure medium hasa first section adjacent to the first end and a second section locatedbetween the first section and the second end, one of the first or secondsections requiring less force to fail than the other of the first orsecond sections.
 38. A crash cushion to minimize the results of acollision between a vehicle and a fixed obstacle, comprising: a failuremedium extending in a first direction and having first and second ends,the failure medium having two edge portions and a center portion locatedbetween the two edge portions, the two edge portions and the centerportion extending in the first direction; a support extending in thefirst direction and coupled to the failure medium along the two edgeportions, with the center portion being free to deform; a cutter mountedon a carriage located adjacent to the first end of the failure medium; atrack extending between the first and second ends, the carriage beingmoveably mounted on the track, the track being oriented so as to allowthe cutter to move longitudinally through the failure medium centerportion between the first and second ends by the cutter deforming thecenter portion and causing the center portion to fail in tension; andpanels that extend along the first direction, the panels being supportedby a framework that is movable in the first direction, the frameworkbeing structured and arranged to maintain its position along the firstdirection when the panels are impacted in a second direction that isperpendicular to the first direction.
 39. The crash cushion of claim 38wherein the framework is movable along the track.
 40. The crash cushionof claim 38 wherein the panels overlap so as to nest when the frameworkis moved to the second end.
 41. The crash cushion of claim 38, wherein:the framework comprises individual frames spaced apart along the firstdirection; and the panels are selectively coupled, either fixedly orslidingly, to the frames in a predetermined pattern.
 42. A crash cushionto minimize the results of a collision between a vehicle and a fixedobstacle, comprising: a failure medium extending in a first directionand having first and second ends, the failure medium having two edgeportions and a center portion located between the two edge portions, thetwo edge portions and the center portion extending in the firstdirection; a support extending in the first direction and being coupledto the failure medium along the two edge portions, with the centerportion being free to deform, the failure medium and the supportstructured and arranged to be located adjacent to ground so as to passbeneath an impacting vehicle; a cutter mounted on a carriage, thecarriage being located adjacent to the first end of the failure medium;and a track extending between the first and second ends, the carriagebeing moveably mounted on the track, the track being oriented so as toallow the cutter to move longitudinally through the failure mediumcenter portion between the first and second ends by the cutter deformingthe center portion and causing the center portion to fail in tension.43. A crash cushion to minimize the results of a collision between avehicle and a fixed obstacle, comprising: a failure medium extending ina first direction and having first and second ends, the failure mediumhaving two edge portions and a center portion located between the twoedge portions, the failure medium comprising one or more metal plates; asupport extending in the first direction and being coupled to thefailure medium along the two edge portions, with the center portionbeing free to deform; a cutter mounted on a carriage, the carriage beinglocated adjacent to the first end of the failure medium, the cutterhaving an edge that engages the failure medium plate, the edge beingoriented at an angle relative to the first direction; a track extendingbetween the first and second ends, the carriage being moveably mountedon the track, the track being oriented so as to allow the cutter to movethrough the failure medium center portion between the first and secondends by the cutter deforming the center portion and causing the centerportion to fail in tension; the support forming a channel extending inthe first direction, the failure medium center portion spanning at leasta portion of the channel, the channel receiving the cutter; the failuremedium having a first section adjacent to the first end and a secondsection located between the first section and the second end, one of thefirst or second sections requiring less force to fail than the other ofthe first or second sections; and panels that extend along the firstdirection, the panels being supported by a framework that is movable inthe first direction, the framework being structured and arranged tomaintain its position along the first direction when the panels areimpacted in a second direction that is perpendicular to the firstdirection, wherein the framework is movable along the track.
 44. Amethod of installing a crash cushion that minimizes the results of acollision between a vehicle and a fixed obstacle, comprising the stepsof: providing a track from the obstacle to a position some distanceaway, the track having a first end at the position and a second endadjacent to the obstacle, the track being oriented so as to be parallelto a direction of vehicle traffic passing near the obstacle; mounting arip medium to ground, the rip medium extending from the first end towardthe second end; providing a carriage having a cutter mounted thereto;and mounting the carriage to the track at the first end and aligning thecutter so as to engage the rip medium when the carriage is pushed towardthe obstacle.
 45. A method of installing a crash cushion that minimizesthe results of a collision between a vehicle and a fixed obstacle,comprising the steps of: providing a track from the obstacle to aposition some distance away, the track having a first end at theposition and a second end adjacent to the obstacle, the track beingoriented so as to be parallel to a direction of vehicle traffic passingnear the obstacle; mounting a rip medium to ground, the rip mediumextending from the first end toward the second end; providing a carriagehaving a cutter mounted thereto; mounting the carriage to the track atthe first end and aligning the cutter so as to engage the rip mediumwhen the carriage is pushed toward the obstacle; and providing a channelthat extends adjacent to the rip medium from the first end toward thesecond end; and wherein the step of aligning the cutter so as to engagethe rip medium filter comprising the step of positioning the cutterwithin the channel.